Medicyte (Germany)

3D structures resembling embryonic liver buds have recently been described using stem cell-derived cell types (Takebe et al., 2013). Such structures can be transplanted into animals/patients but may also be useful for applications like ex vivo drug toxicity tests. We here used differentiated upcyte® cells which are derived from primary human cells that underwent targeted genetic modification (upcyte® process) in order to transiently induce or extend proliferation resulting in mortal, but expandable, differentiated cells. upcyte® cells can undergo up to 40 additional population doublings, and when contact-inhibited they differentiate into functional cells while maintaining most of their specific characteristics.

We have developed a new technology to allow the proliferation of differentiated primary cells without inducing permanent immortalization, uncontrolled cell growth, or loss of phenotype. The Upcyte® (“upregulated”) technology involves a viral gene transfer system to introduce a unique combination of genes that induce and maintain cell proliferation until the cells reach confluence. This allows the primary cells to be passaged many times with the generation of billions of cells. Upcyte® technology can be applied to different cell types such as hepatocytes. Here, we summarise some of the comparisons we have made between primary hepatocytes and the upcyte® hepatocytes derived thereof. Metabolic enzymes: CYP activities e.g. CYP3A4, CYP2C8 and CYP2B6, are expressed in significant abundance and, moreover, can be induced by prototypical inducers. For example, rifampicin mediated CYP3A4 induction responses of upcyte® hepatocytes from over 5 donors by now were in line with the FDA guideline pass criteria. Furthermore induction potential was stable over the course of expansion. Application of upcyte® cells as optimal alternatives to current in vitro screening assays: Upcyte® technology allows for the mass production of primary cells from different organs and donors for use in multiple in vitro ADME-Tox assays. The flexibility of the application of upcyte® cells to different cellular-based assays, together their abundant availability from different donors for routine testing means models are now available with sustained quality and sufficient quantities to allow for reproducible and reliable in vitro ADMET studies. Since upcyte® technology allows for the generation of hepatocytes with differentiated function, they offer a unique advantage of combining the phenotype of primary hepatocytes with the virtually unlimited availability and ease of handling human tumour cells and cell lines.